The commandant of the Marine Corps says that a budget-constrained force of 174,000 — but no lower — provides the nation with an amphibious force that balances ongoing operational requirements with crisis-response capabilities, although it assumes increased risk in the event of war.

In a 3,000-word essay, published in the November edition of the U.S. Naval Institute’s Proceedings magazine, Gen. Jim Amos argues that national security and economic vitality are intertwined, and both depend on robust naval expeditionary capabilities that the Marine Corps-Navy partnership provides. Its publication comes just days before Amos and the other service chiefs are due to testify before the Senate Armed Services Committee regarding planning and the impacts of the long-term budget cuts known as sequestration.

In February, the Marine Corps participated in a Pentagon-wide Strategic Choices and Management Review, which envisioned a variety of force strengths and capabilities based on budget-cutting requirements. At the review’s release, Defense Secretary Chuck Hagel said the Marine Corps’ end strength would rest between 150,000 and 174,000 by the end of 2016. The figures represented a steep drop for the Corps, which had outlined a strategy to “right-size” from 202,000 to 186,800 following its 2010 Force Structure Review Group, but later revised its end strength goal to 182,100 amid cutbacks required by the 2011 Budget Control Act.

Force-shaping cuts to the Marine Corps driven by budget constraints come at a timewhen Marines are being asked to do more then they ever have before, including the relatively recent addition of special operations and cyber warfare capabilities, Amos writes.

“This was not easy, but would prove fruitful as it gave us the best force available given our reduced resource levels,” Amos wrote. “The idea was to not ‘do more with less,’ but to do as much as we could, as efficiently as possible, and do it well.”

Amos first publicly addressed the prospect of a force of 174,000 before the House Armed Services Committee in September, stressing the dire realities of cutting the Corps that deeply. He said the aggressive re-shaping would leave the Marines at a “minimum acceptable” level of readiness and added that “Marines who join the Corps during that period would likely go from the drill field to the battlefield.”

In his USNI essay, Amos casts the 174K force instead as a favorable alternative to other options, still on the table, that would whittle the Corps thinner.

“At the end of the day, a 174K Marine Corps gives America the best balance of the requirements of steady-state operations and crisis-response activities while accepting increased risk in major contingency operations. ... Going below 174K would upset a critical balance of being able to provide a ready force, meet steady-state demand, and respond to crisis — exposing substantially greater risk across the board,” he wrote.

Amos also discusses in unprecedented depth how Marine officials modeled what a strategic Marine Corps force structure might look like for a range of end strengths offered up by the Pentagon.

“Based on guiding principles and driven by fiscal constraints, our working group built a set of force structures focused on meeting emerging demands,” he wrote. “The ‘prime force’ encompassed an array of scalable force structures designed as a set of building blocks, called capability shells.

They first layered in “fenced” forces, institutional activities that are protected from major cuts. He listed Marine Corps Cyber Command, Marine Corps Forces Special Operations Command, Chemical Biological Incident Response Force, Marine Barracks Washington, and Marine Aviation Weapon and Tactics Squadron 1 among these fenced forces. But as the Marine Corps Times recently reported, MARSOC growth plans will also fall victim to budgetary belt-tightening.

Last month Maj. Gen. Frank McKenzie, the Marine Corps representative to the Pentagon’s Quadrennial Defense Review, described a number of other strengths Marine officials wanted to protect from substantial cuts, including Marine expeditionary units, and training and base support capabilities, as well as key acquisition projects such as the F-35B Joint Strike Fighter and the Joint Light Tactical Vehicle.

The bulk of the cuts, officials said, will be directed at headquarters staffs and the largest Marine communities, such as infantry battalions and artillery battalions, and aviation elements.

Amos said after the fenced forces were layered in, Marine officials added capability shells “such that the force could address the highest-priority risks and enhance desired capabilities.”

Only one force-structure design — a force of 174,000 Marines — “possessed the capacity to sustain forward presence requirements at a unit deployed-to-dwell ratio of 1:2 while also maintaining the capability to respond to a single, moderate crisis for an extended period of time,” he wrote.

In addition, the 174K force gives the Marine Corps the ability to add capabilities back in if circumstances demand.

“More important, this approach to force design will allow us to regain wholeness of our force while reducing risk and maintaining balance, vice the typical piecemeal fashion we’ve seen in the past,” he said, referring to prior aggressive force cuts such as those taken during the Depression era prior to World War II.

What remains to be seen is if the Marines will be permitted to keep and end strength of 174K and be exempted from more bitter cuts. The results of the QDR are expected in February 2014. Amos will make his case to the members of the Senate Armed Services Committee Nov. 7.